Assembling a perforating gun string within a casing string

ABSTRACT

Methods are disclosed for assembling a perforating gun string in a wellbore. One method includes assembling a first perforating gun assembly into a lubricator, connecting the lubricator to a blowout preventer coupled to a wellhead, lowering the first perforating gun assembly on a conveyance into the blowout preventer, engaging the first perforating gun assembly with sealing rams of the blowout preventer, detaching the conveyance from the first perforating gun assembly and removing the conveyance from the blowout preventer, disconnecting the lubricator from the blowout preventer, assembling a second perforating gun assembly into the lubricator, re-connecting the lubricator to the blowout preventer, lowering the second perforating gun assembly into the blowout preventer and attaching the second perforating gun assembly to the first perforating gun assembly, and repeating the process to form a perforating gun string.

BACKGROUND

The present disclosure relates generally to wellbore casing perforation operations and, more particularly, to assembling multiple perforating gun assemblies into a perforating gun string within a casing string in a wellbore and/or a blowout preventer operatively and fluidly coupled thereto.

After drilling the various sections of a subterranean wellbore that traverses a hydrocarbon-bearing formation, individual lengths of relatively large diameter metal tubulars are typically secured together to form a casing string that is positioned within the wellbore. This casing string increases the integrity of the wellbore and provides a path for producing fluids extracted from producing intervals in the formation to the surface. Conventionally, the casing string is cemented within the wellbore. To produce fluids into the casing string, hydraulic openings or perforations must be made through the casing string and the cement, and extend a short distance into the surrounding subterranean formation.

Typically, these perforations are created by detonating a series of shaped charges that are disposed within the casing string and are positioned adjacent to the formation. Specifically, one or more perforating guns are loaded with shaped charges and include a firing head. The perforating guns are then connected within a tool string that is lowered into the cased wellbore at the end of a conveyance. Once the perforating guns are properly positioned in the wellbore such that the shaped charges are adjacent the formation to be perforated, the firing head is actuated and the shaped charges detonate, thereby creating the desired hydraulic openings in to the casing string. Then, the perforating guns are retrieved at the well head. This process of running, detonating, and retrieving perforating guns is repeated several times to achieve the desired perforation operation.

BRIEF DESCRIPTION OF THE DRAWINGS

The following figures are included to illustrate certain aspects of the present disclosure, and should not be viewed as exclusive embodiments. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, without departing from the scope of this disclosure.

FIG. 1 provides an illustration of a perforating gun assembly loaded in a lubricator.

FIG. 2 provides an illustration of a lubricator connected to a blowout preventer and wellbore therebelow.

FIG. 3 provides an illustration of sealing rams of a blowout preventer engaged with a subassembly of a perforating gun assembly.

FIG. 4 provides an illustration of a conveyance retracted from a blowout preventer and into a lubricator.

FIG. 5 provides an illustration of a perforating gun assembly loaded in a lubricator.

FIG. 6 provides an illustration of a second perforating gun assembly attached to a first perforating gun assembly while arranged in a blowout preventer fluidly connected to a casing string.

FIG. 7 provides an illustration of sealing rams of a blowout preventer engaged with a subassembly of a second perforating gun assembly that itself is attached to a first perforating gun assembly.

FIG. 8 provides an illustration of a perforating gun string assembled within a blowout preventer and extended into a casing string.

DETAILED DESCRIPTION

The present disclosure relates generally to wellbore casing perforation operations and, more particularly, to assembling multiple perforating gun assemblies into a perforating gun string within a casing string in a wellbore and/or a blowout preventer operatively and fluidly coupled thereto.

The methods and systems described herein allow an operator to run multiple perforating gun clusters into a wellbore in a single run as an elongate perforating gun string. In some instances, the resulting perforating gun string may be hundreds of feet long (e.g., in excess of 600 feet in some instances). By reducing the total number of runs required for a wellbore perforation operation, the cost and time associated with the wellbore perforation operation may be reduced.

Further, the methods and system described herein may be used in newly drilled and cased wells or in live wells. Typically, live wells are under significant pressure, which reduces an operator's ability to run tools downhole. The methods and systems described herein, in some instances, utilize seals and rams associated with a blowout preventer and a lubricator for providing pressure isolation during the assembly of the perforating gun string, which allows for implementation of the methods and systems in conjunction with live wells. Those skilled in the art will readily recognize that additional perforation operations in live wells may be useful in stimulating additional or increased hydrocarbon production.

FIGS. 1-8 illustrate at least some of the steps of the methods described herein for assembling multiple perforating gun assemblies 102 within a casing string 106 secured within a wellbore 126. As illustrated, the casing string 106 is coupled to and otherwise extends from a wellhead 104 arranged at a surface location. While FIGS. 1-8 generally depict a land-based operation, those skilled in the art will readily recognize that the principles described herein are equally applicable to subsea operations that employ floating or sea-based platforms and rigs, without departing from the scope of the disclosure. Further, it should be understood that the methods provided herein are applicable to perforating the casing string 106 in a wellbore 126 at any angle including, but not limited to, vertical wells, deviated wells, highly deviated wells, horizontal wells, and hybrid wells comprising sections of any combination of the aforementioned wells. As used herein, the term “deviated wellbore” refers to a wellbore in which any portion of the well is that is oriented between about 55-degrees and about 125-degrees from a vertical inclination. As used herein, the term “highly deviated wellbore” refers to a wellbore that is oriented between about 75-degrees and about 105-degrees off vertical.

As illustrated in FIG. 1, a hydraulic workover blowout preventer 118 (“BOP 118”) may be coupled to the wellhead 104 and a lubricator 108 may be removably coupled to the top of the BOP 118. In the illustrated embodiment, the lubricator 108 is depicted as being detached from the BOP 118 such that a first perforating gun assembly 102 a may be strategically loaded into the lubricator 108 and attached to a conveyance 110. Examples of conveyances 110 suitable for use in the embodiments described herein may include, but are not limited to, coiled tubing, ecoil tubing, wireline, threaded pipe, and the like. In the event that wireline is used as the conveyance 110, it may be required to pump the perforating gun assemblies 102 downhole within the casing string 106.

The first perforating gun assembly 102 a includes a first subassembly 112 a and, in alternating order, a plurality of extended delay assemblies 114 and perforating gun clusters 116. The first subassembly 112 a may be configured to be captured or otherwise engaged by sealing rams of the BOP 118. As will be recognized by one of skill in the art, the first perforating gun assembly 102 a may have a variety of configurations, without departing from the scope of the disclosure. For instance, while only three extended delay assemblies 114 and three perforating gun clusters 116 are depicted in FIG. 1, it will be appreciated that more or less than three may be used, without departing from the scope of the disclosure. Moreover, in other embodiments, the first perforating gun assembly 102 a may include two or more perforating gun clusters 116 abutting, a perforating gun cluster 116 or an extended delay assembly 114 being connected to a conveyance 110 with the first subassembly 112 a included elsewhere within the first perforating gun assembly 102 a, and any combination of the foregoing. In some instances, the first perforating gun assembly 102 a may terminate with a bull plug (not shown).

Examples of subassemblies 112 suitable for use in the embodiments described herein may include, but are not limited to, an isolation subassembly, such as is described in co-owned U.S. Pat. No. 5,529,127, and a detonation transfer subassembly, such as is disclosed in co-owned U.S. Pat. No. 6,675,896.

The length of the first perforating gun assembly 102 a, and any of the perforating gun assemblies described herein below, may be capable of fitting axially within the lubricator 108. In some embodiments, for instance, the axial length of the first perforating gun assembly 102 a, and any of the perforating gun assemblies described herein below, may range from about 10 feet to about 65 feet, depending on the number of extended delay assemblies 114 and perforating gun clusters 116 employed and the structural limitations of the lubricator 108.

After assembling the first perforating gun assembly 102 a into the lubricator 108, the lubricator 108 may be connected to the BOP 118, as illustrated in FIG. 2. One skilled in the art will recognize that equipment suitable for manipulating the position of the lubricator 108 with respect to the BOP 118 as described herein may include, but is not limited to, a crane, a derrick, a riser, and the like.

The BOP 118 includes a series of rams, seals, and slips that allow for isolating portions the lubricator 108 from the casing string 106. For example, the BOP 118 may include blind rams 120 that operate to substantially isolate the lubricator 108 from the casing string 106, which may be useful when the casing string 106 is pressurized (e.g., in a live well). One skilled in the art will recognize that other rams and seals may be included within the BOP 118 (e.g., annular rams) and may equally be used or otherwise engaged in order to perform the methods described herein and abide by safety regulations.

After attaching the lubricator 108 to the BOP 118, some embodiments may involve pressure testing the lubricator 108 and the conveyance 110. Once proper pressure testing has been accomplished, the blind rams 120 in the BOP 118 may be opened and the first perforating gun assembly 102 a may then be lowered into the BOP 118 using the conveyance 110.

As illustrated in FIG. 3, the first perforating gun assembly 102 a may be positioned or otherwise lowered in the BOP 118 so that sealing rams 122 of the BOP 118 are able to engage the first subassembly 112 a, thereby securing the first perforating gun assembly 102 a within the BOP 118. In an alternate embodiment, the sealing rams 122 may be positioned within the BOP 118 such that the first subassembly 112 a extends out of the BOP 118 when engaged with the sealing rams 122.

Referring now to FIG. 4, the conveyance 110 may then be detached from the first perforating gun assembly 102 a and retracted from the BOP 118. In some instances, the blind rams 120 may be re-engaged within the BOP 118 so that the fluid pressure within the lubricator 108 can be reduced or bled off.

As illustrated in FIG. 5, once the fluid pressure within the lubricator 108 reduced, the lubricator 108 may then be disconnected once again from the BOP 118 and a second perforating gun assembly 102 b may be assembled and loaded into the lubricator 108. The second perforating gun assembly 102 b may be attached to the conveyance 110 as it is assembled into the lubricator 108. Similar to the first perforating gun assembly 102 a, the second perforating gun assembly 102 b may include a second subassembly 112 b, and one or more extended delay assemblies 114 (three shown) and one or more perforating gun clusters 116 (three shown) arranged in an alternating pattern or otherwise, as generally described above. In some instances, two lubricators 108 may be used (not shown) so that as a first lubricator is disconnected from the BOP, the second lubricator can be connected to the BOP where method steps described herein are performed consistent with the location of the lubricator relative to the BOP.

As illustrated in FIG. 6, the lubricator 108 with the second perforating gun assembly 102 b assembled or otherwise disposed therein may be connected to the BOP 118. The lubricator 108 and conveyance 110 may then be pressure tested in order to normalize pressures between the BOP 118 and the lubricator 108. Once the pressure tests have been undertaken, the second perforating gun assembly 102 b may then be lowered into the BOP 118 on the conveyance 110 and attached to the first perforating gun assembly 102 a still secured within the BOP 118 at the sealing rams 122. The result is the formation of a portion of a perforating gun string 124 encompassing the first and second perforating gun assemblies 102 a,b. One skilled in the art will recognize the appropriate configuration of ends of the first perforating gun assembly 102 a and the second perforating gun assembly 102 b to effect attachment. For example, a perforating gun cluster 116 of the second perforating gun assembly 102 b may be configured for ready attachment to the first subassembly 112 a of the first perforating gun assembly 102 a.

The sealing rams 122 may then be disengaged from the first subassembly 112 a, thereby freeing the first perforating gun assembly 102 a and the entire perforating gun string 124 for axial movement within the BOP 118 and the casing string 106 arranged there below. The perforating gun string 124 may therefore be lowered at least partially into the casing string 106 or to a position where the sealing rams 122 may engage the second subassembly 112 b.

As illustrated in FIG. 7, after engagement, the conveyance 110 may then be detached from the second perforating gun assembly 102 b and retracted from the BOP 118. Again the blind rams 120 within the BOP 118 may be engaged as needed for pressure isolation purposes.

As illustrated in FIG. 8, the above-described process of assembling and attaching additional perforating gun assemblies 102 to the perforating gun string 124 may be repeated and otherwise continued until a last or final perforating gun assembly 102 z is attached to the top of the perforating gun string 124, thereby completing the length of the perforating gun string 124. In some instances, a subassembly may not be included with the final perforating gun assembly 102 z. In FIG. 8, the final perforating gun assembly 102 z is depicted as including a firing head 128, one or more extended delay assemblies 114 (three shown) and one or more perforating gun clusters 116 (three shown) arranged in an alternating pattern or otherwise, as generally described above. The sealing rams 122 may then be disengaged from a subassembly 112 y of a penultimate perforating gun assembly 102 y. Then, the entire perforating gun string 124 may be lowered into the casing string 106 using the conveyance 110 to a desired or predetermined location.

As will be appreciated, the number of perforating gun assemblies 102 a-z used to assemble the entire length of the perforating gun string 124 may depend on the size of the lubricator 108 and the desired length of the perforating gun string 124 to achieve the perforating operation. In some embodiments, the number of perforating gun assemblies 102 a-z used to form the perforating gun string 124 may range from about 2 to about 50 and may even range to about 75 or about 100, in some embodiments. In some embodiments, the resulting length of the perforating gun string 124 may range from about 50 feet to about 800 feet.

Generally, either the first or the final perforating gun assemblies 102 a,z will include a firing head 128. Once locating a desired location within the wellbore 126, the firing head may be actuated or otherwise activated in order to start the firing sequence of the perforating gun string 124. In some instances, incorporation of the extended delay assemblies 114 in the perforating gun assemblies 102 a-z may allow a well operator to reposition the perforating gun string 124 one or more times during delay times associated with the firing sequence.

Retrieval of the perforating gun string 124 after firing is generally the reverse method of assembling the perforating gun string 124. More particularly, the perforating gun string 124 may be pulled back into the BOP 118 until the subassembly 112 y of the perforating gun assembly 102 y connected to the final perforating gun assembly 102 z is positioned once again to engage the sealing rams 122, as illustrated in FIG. 8. After engaging the sealing rams 122, the final perforating gun assembly 102 z may be detached from the previous perforating gun assembly 102 y and pulled into the lubricator 108 on the conveyance 110. The lubricator 108 may then be disconnected once again from the BOP 118 and the final perforating gun assembly 102 z removed therefrom and detached from the conveyance 110. This process may be repeated and continue until all perforating gun assemblies 102 a-z are removed from the BOP 118 and the perforating gun string 124 is entirely disassembled.

The various steps of attachments and connections described herein can be achieved with a variety of mechanical connectors or connection devices. Such mechanical connectors or connection devices may include, but are not limited to, threaded connectors, autolatch connectors (such as those described in U.S. Pat. No. 5,992,523), ratchet connectors (such as those described in U.S. Pat. No. 6,843,320), combinations thereof, and the like.

Some embodiments of the present disclosure include variations of the foregoing methods. For example, the steps of loading a perforating gun assembly into the lubricator and attaching the perforating gun assembly to the conveyance may be performed in any order. Further, the perforating gun assembly may be assembled by running the conveyance through the lubricator, attaching a first portion of the perforating gun assembly to the conveyance, conveying the first portion of the perforating gun assembly into at least a portion of the lubricator, attaching a second portion of the perforating gun assembly to the first portion of the perforating gun assembly, and so on until the first perforating gun assembly is assembled and contained within the lubricator.

In some instance, as described above, the subassemblies may include at least one detonation transfer subassembly. Generally, a detonation transfer subassembly is configured so that, when engaged by a shear ram, the detonation transfer subassembly will sever without detonating a perforating gun cluster adjacent thereto. In some instances during insertion or extraction, where an unexpected pressure increase in the well is experienced, the perforating gun string or portion thereof may be conveyed to a position where a shear ram of the blowout preventer can engage a detonation transfer subassembly. Because at least some of the embodiments described herein may be performed with a live well, this feature may advantageously provide for enhanced safety protocols in preventing or containing a well blowout.

Embodiments disclosed herein include:

Embodiment A: a method that comprises (a) assembling a first perforating gun assembly into a lubricator, the first perforating gun assembly including at least one perforating gun cluster, at least one extended delay assembly, and a first subassembly; (b) connecting the lubricator with the first perforating gun assembly disposed therein to a blowout preventer coupled to a wellhead; (c) lowering the first perforating gun assembly on a conveyance into at least a portion of the blowout preventer; (d) engaging the first subassembly with sealing rams included in the blowout preventer; (e) detaching the conveyance from the first perforating gun assembly and removing the conveyance from the blowout preventer; (f) disconnecting the lubricator from the blowout preventer; (g) assembling a second perforating gun assembly into the lubricator, the second perforating gun assembly including at least one perforating gun cluster, at least one extended delay assembly, and a second subassembly; (h) connecting the lubricator with the second perforating gun assembly disposed therein to the blowout preventer; (i) lowering the second perforating gun assembly into the blowout preventer and attaching the second perforating gun assembly to the first perforating gun assembly, thereby forming a portion of a perforating gun string; (j) disengaging the sealing rams from the first subassembly; (k) lowering the portion of the perforating gun string through at least a portion of the blowout preventer; (l) engaging the second subassembly with the sealing rams of the blowout preventer; (m) detaching the conveyance from the portion of the perforating gun string; (n) repeating steps (f)-(m) as desired until a final perforating gun assembly is attached to the portion of the perforating gun string, thereby forming the perforating gun string, wherein at least one of the first and final perforating gun assemblies includes a firing head, and wherein the final perforating gun assembly optionally comprises a corresponding subassembly; (o) disengaging the sealing rams from a subassembly of a penultimate perforating gun assembly; (p) conveying the perforating gun string to a desired location within a wellbore extending from the wellhead and penetrating a subterranean formation; and (q) actuating the firing head.

Embodiment B: a method that comprises (a) loading a first perforating gun assembly into a lubricator, wherein the first perforating gun assembly comprises, in order, a first subassembly and in alternating order a first plurality of extended delay assemblies and perforating gun clusters; (b) attaching the first perforating gun assembly to a coiled tubing; (c) connecting the lubricator with the first perforating gun assembly disposed therein to a blowout preventer coupled to a wellhead that is fluidly connected to a casing string disposed within a wellbore; (d) pressure testing the lubricator; (e) opening blind rams of the blowout preventer disposed between sealing rams of the blowout preventer and the lubricator; (f) conveying the first perforating gun assembly past the blind rams; (g) engaging the sealing rams on the first subassembly; (h) detaching the first perforating gun assembly from the coiled tubing; (i) retracting the coiled tubing into the lubricator; (j) closing the blind rams; (k) depressurizing the lubricator; (l) disconnecting the lubricator from the blowout preventer; (m) loading a second perforating gun assembly into the lubricator, wherein the second perforating gun assembly comprises, in order, a second subassembly and in alternating order a second plurality of extended delay assemblies and perforating gun clusters; (n) attaching the second perforating gun assembly to the coiled tubing; (o) connecting the lubricator with the second perforating gun assembly disposed therein to the blowout preventer; (p) pressure testing the lubricator; (q) opening the blind rams of the blowout preventer; (r) attaching the second perforating gun assembly to the first perforating gun assembly, and thereby forming a portion of a perforating gun string; (s) disengaging the sealing rams from the first subassembly; (t) lowering the portion of the perforating gun string within the blowout preventer; (u) engaging the sealing rams on the second subassembly; (v) detaching the portion of the perforating gun string from the coiled tubing; (w) repeating steps of (i)-(v) as desired until a final perforating gun assembly is attached to a penultimate perforating gun assembly, and thereby forming the perforating gun string, wherein at least one of the first and final perforating gun assemblies comprise a firing head, and wherein the final perforating gun assembly optionally comprises a corresponding subassembly; (x) disengaging the sealing rams from a subassembly of the penultimate perforating gun assembly; (y) conveying the perforating gun string with the coiled tubing to a desired location within the wellbore; and (z) actuating the firing head.

In some instances, Embodiments A and B may further include at least one of the following elements in any combination: Element 1: wherein the conveyance extends into the lubricator and assembling the first perforating gun assembly into the lubricator comprises: (1) attaching a first portion of the first perforating gun assembly to the conveyance; (2) conveying the first portion of the first perforating gun assembly into a portion of the lubricator; (3) attaching a second portion of the first perforating gun assembly to the first portion of the first perforating gun assembly; and repeating steps (2) and (3) to assemble additional portions of the first perforating gun assembly until the first perforating gun assembly is assembled and contained within the lubricator; Element 2: wherein the subassemblies are at least one of an isolation subassembly and a detonation transfer subassembly; Element 3: wherein assembling the first perforating gun assembly into the lubricator comprises coupling the first subassembly to a plurality extended delay assemblies and a plurality of perforating gun clusters, where the pluralities of extended delay assemblies and perforating gun clusters alternate along a length of the first perforating gun assembly and extend from the first subassembly; Element 4: Element 3 further comprising arranging a bull plug at a distal end of the first perforating gun assembly; Element 5: wherein the conveyance is at least one of a coiled tubing, an ecoil tubing, a wireline, a threaded pipe, and any hybrid thereof; Element 6: wherein the wellbore includes a casing string secured therein and the wellbore is under pressure; Element 7: wherein at least a portion of the wellbore is a deviated wellbore; Element 8: wherein the first perforating gun assembly is the penultimate perforating gun assembly and the second perforating gun assembly is the final perforating gun assembly; and Element 9: wherein the first subassembly extends from the blowout preventer when engaged with the sealing rams. By way of non-limiting example, exemplary combinations may include Element 2 in combination with Element 6; Element 4 in combination with Element 6 and optionally in combination with Element 2; Element 8 in combination with at least one of Elements 1-7; Element 1 in combination with Element 5; Element 9 in combination with any of the foregoing; and Element 9 in combination with at least one of Elements 1-8.

Embodiments disclosed herein also include Embodiment C: a method that comprise (a) actuating a firing head of a perforating gun string disposed within a casing string of a wellbore penetrating a subterranean formation, the perforating gun string comprising a plurality of perforating gun assemblies; (b) drawing the perforating gun string into a blowout preventer with a conveyance such that a first perforating gun assembly passes sealing rams of the blowout preventer; (c) engaging the sealing rams with a subassembly of a second perforating gun assembly; (d) detaching the first perforating gun assembly from the second perforating gun assembly; (f) drawing the first perforating gun assembly from the blowout preventer into a lubricator on the conveyance; (g) disconnecting the lubricator from the blowout preventer; (h) removing the first perforating gun assembly from the lubricator; (i) detaching the conveyance from the first perforating gun assembly; (j) attaching the lubricator to the blowout preventer; (k) attaching the conveyance to the subassembly of the second perforating gun assembly; (l) disengaging the sealing rams of the blowout preventer from the subassembly of the second perforating gun assemblies; and (m) repeating steps (b)-(l) as desired until the plurality of perforating gun assemblies has been removed. Some embodiments may further include at least one of the following elements in any combination: Element 10: wherein steps (h) and (i) comprise: (1) detaching a first portion of the first perforating gun assembly from the first perforating gun assembly; (2) conveying a remaining portion of the first perforating gun assembly through a portion of the lubricator; (3) detaching a second portion of the first perforating gun assembly from the remaining portion of the first perforating gun assembly; and repeating steps (2) and (3) for additional portions of the first perforating gun assembly until the first perforating gun assembly is fully disassembled; Element 11: wherein the first perforating gun assembly comprises, in order, a first subassembly, and corresponding alternating pluralities of extended delay assemblies and perforating gun clusters; Element 12: wherein the conveyance is at least one of a coiled tubing, an ecoil tubing, a wireline, a threaded pipe, and any hybrid thereof; Element 13: wherein the wellbore is under pressure; Element 14: wherein at least a portion of the wellbore is a deviated wellbore; Element 15: wherein the subassemblies are at least one of an isolation subassembly and a detonation transfer subassembly; and Element 16: wherein the subassembly of the second perforating gun assembly extends from the blowout preventer when engaged with the sealing rams. By way of non-limiting example, exemplary combinations may include Element 13 in combination with Element 14; Element 13 in combination with Element 15 and optionally in combination with Element 14; Element 10 in combination with Element 11; Element 16 in combination with any of the foregoing; and Element 16 in combination with at least one of Elements 10-15.

Unless otherwise indicated, all numbers expressing quantities, measurements, and so forth used in the present specification and associated claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the embodiments of the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claim, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

In some instances, not all features of a physical implementation are described or shown in this application for the sake of clarity. It is understood that in the development of a physical embodiment incorporating the embodiments of the present invention, numerous implementation-specific decisions must be made to achieve the developer's goals, such as compliance with system-related, business-related, government-related and other constraints, which vary by implementation and from time to time. While a developer's efforts might be time-consuming, such efforts would be, nevertheless, a routine undertaking for those of ordinary skill the art and having benefit of this disclosure.

Therefore, the disclosed systems and methods are well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the teachings of the present disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered, combined, or modified and all such variations are considered within the scope of the present disclosure. The systems and methods illustratively disclosed herein may suitably be practiced in the absence of any element that is not specifically disclosed herein and/or any optional element disclosed herein. While compositions and methods are described in terms of “comprising,” “containing,” or “including” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps. All numbers and ranges disclosed above may vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the element that it introduces. If there is any conflict in the usages of a word or term in this specification and one or more patent or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted.

As used herein, the phrase “at least one of” preceding a series of items, with the terms “and” or “or” to separate any of the items, modifies the list as a whole, rather than each member of the list (i.e., each item). The phrase “at least one of” does not require selection of at least one item; rather, the phrase allows a meaning that includes at least one of any one of the items, and/or at least one of any combination of the items, and/or at least one of each of the items. By way of example, the phrases “at least one of A, B, and C” or “at least one of A, B, or C” each refer to only A, only B, or only C; any combination of A, B, and C; and/or at least one of each of A, B, and C.

The use of directional terms such as above, below, upper, lower, upward, downward, left, right, uphole, downhole and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward direction being toward the top of the corresponding figure and the downward direction being toward the bottom of the corresponding figure, the uphole direction being toward the surface of the well and the downhole direction being toward the toe of the well. 

1. A method comprising: (a) assembling a first perforating gun assembly into a lubricator, the first perforating gun assembly including at least one perforating gun cluster, at least one extended delay assembly, and a first subassembly; (b) connecting the lubricator with the first perforating gun assembly disposed therein to a blowout preventer coupled to a wellhead; (c) lowering the first perforating gun assembly on a conveyance into at least a portion of the blowout preventer; (d) engaging the first subassembly with sealing rams included in the blowout preventer; (e) detaching the conveyance from the first perforating gun assembly and removing the conveyance from the blowout preventer; (f) disconnecting the lubricator from the blowout preventer; (g) assembling a second perforating gun assembly into the lubricator, the second perforating gun assembly including at least one perforating gun cluster, at least one extended delay assembly, and a second subassembly; (h) connecting the lubricator with the second perforating gun assembly disposed therein to the blowout preventer; (i) lowering the second perforating gun assembly into the blowout preventer and attaching the second perforating gun assembly to the first perforating gun assembly, thereby forming a portion of a perforating gun string; (j) disengaging the sealing rams from the first subassembly; (k) lowering the portion of the perforating gun string through at least a portion of the blowout preventer; (l) engaging the second subassembly with the sealing rams of the blowout preventer; and (m) detaching the conveyance from the portion of the perforating gun string.
 2. The method of claim 1 further comprising: (n) repeating steps (f)-(m) as desired until a final perforating gun assembly is attached to the portion of the perforating gun string, thereby forming the perforating gun string, wherein at least one of the first and final perforating gun assemblies includes a firing head, and wherein the final perforating gun assembly optionally comprises a corresponding subassembly; (o) disengaging the sealing rams from a subassembly of a penultimate perforating gun assembly; (p) conveying the perforating gun string to a desired location within a wellbore extending from the wellhead and penetrating a subterranean formation; and (q) actuating the firing head.
 3. The method of claim 1, wherein the conveyance extends into the lubricator and assembling the first perforating gun assembly into the lubricator comprises: (1) attaching a first portion of the first perforating gun assembly to the conveyance; (2) conveying the first portion of the first perforating gun assembly into a portion of the lubricator; (3) attaching a second portion of the first perforating gun assembly to the first portion of the first perforating gun assembly; and repeating steps (2) and (3) to assemble additional portions of the first perforating gun assembly until the first perforating gun assembly is assembled and contained within the lubricator.
 4. The method of claim 1, wherein the subassemblies are at least one of an isolation subassembly and a detonation transfer subassembly.
 5. The method of claim 1, wherein assembling the first perforating gun assembly into the lubricator comprises coupling the first subassembly to a plurality extended delay assemblies and a plurality of perforating gun clusters, where the pluralities of extended delay assemblies and perforating gun clusters alternate along a length of the first perforating gun assembly and extend from the first subassembly.
 6. The method of claim 5, further comprising arranging a bull plug at a distal end of the first perforating gun assembly.
 7. The method of claim 1, wherein the conveyance is at least one of a coiled tubing, an ecoil tubing, a wireline, a threaded pipe, and any hybrid thereof.
 8. The method of claim 1, wherein the wellbore includes a casing string secured therein and the wellbore is under pressure.
 9. The method of claim 1, wherein at least a portion of the wellbore is a deviated wellbore.
 10. The method of claim 1, wherein the first perforating gun assembly is a penultimate perforating gun assembly and the second perforating gun assembly is the a perforating gun assembly.
 11. A method comprising: (a) actuating a firing head of a perforating gun string disposed within a casing string of a wellbore penetrating a subterranean formation, the perforating gun string comprising a plurality of perforating gun assemblies; (b) drawing the perforating gun string into a blowout preventer with a conveyance such that a first perforating gun assembly passes sealing rams of the blowout preventer; (c) engaging the sealing rams with a subassembly of a second perforating gun assembly; (d) detaching the first perforating gun assembly from the second perforating gun assembly; (e) drawing the first perforating gun assembly from the blowout preventer into a lubricator on the conveyance; (f) disconnecting the lubricator from the blowout preventer; (g) removing the first perforating gun assembly from the lubricator; (h) detaching the conveyance from the first perforating gun assembly; (i) attaching the lubricator to the blowout preventer; (j) attaching the conveyance to the subassembly of the second perforating gun assembly; (k) disengaging the sealing rams of the blowout preventer from the subassembly of the second perforating gun assemblies; and (l) repeating steps (b)-(k) as desired until the plurality of perforating gun assemblies has been removed.
 12. The method of claim 11, wherein the wellbore is under pressure.
 13. The method of claim 11, wherein steps (g) and (h) comprise: (1) detaching a first portion of the first perforating gun assembly from the first perforating gun assembly; (2) conveying a remaining portion of the first perforating gun assembly through a portion of the lubricator; (3) detaching a second portion of the first perforating gun assembly from the remaining portion of the first perforating gun assembly; and repeating steps (2) and (3) for additional portions of the first perforating gun assembly until the first perforating gun assembly is fully disassembled.
 14. The method of claim 11, wherein the first perforating gun assembly comprises, in order, a first subassembly, and corresponding alternating pluralities of extended delay assemblies and perforating gun clusters.
 15. The method of claim 11, wherein the conveyance is at least one of a coiled tubing, an ecoil tubing, a wireline, a threaded pipe, and any hybrid thereof.
 16. The method of claim 11, wherein at least a portion of the wellbore is a deviated wellbore.
 17. A method comprising: (a) loading a first perforating gun assembly into a lubricator, wherein the first perforating gun assembly comprises, in order, a first subassembly and in alternating order a first plurality of extended delay assemblies and perforating gun clusters; (b) attaching the first perforating gun assembly to a coiled tubing; (c) connecting the lubricator with the first perforating gun assembly disposed therein to a blowout preventer coupled to a wellhead that is fluidly connected to a casing string disposed within a wellbore; (d) pressure testing the lubricator; (e) opening blind rams of the blowout preventer disposed between sealing rams of the blowout preventer and the lubricator; (f) conveying the first perforating gun assembly past the blind rams; (g) engaging the sealing rams on the first subassembly; (h) detaching the first perforating gun assembly from the coiled tubing; (i) retracting the coiled tubing into the lubricator; (j) closing the blind rams; (k) depressurizing the lubricator; (l) disconnecting the lubricator from the blowout preventer; (m) loading a second perforating gun assembly into the lubricator, wherein the second perforating gun assembly comprises, in order, a second subassembly and in alternating order a second plurality of extended delay assemblies and perforating gun clusters; (n) attaching the second perforating gun assembly to the coiled tubing; (o) connecting the lubricator with the second perforating gun assembly disposed therein to the blowout preventer; (p) pressure testing the lubricator; (q) opening the blind rams of the blowout preventer; (r) attaching the second perforating gun assembly to the first perforating gun assembly, and thereby forming a portion of a perforating gun string; (s) disengaging the sealing rams from the first subassembly; (t) lowering the portion of the perforating gun string within the blowout preventer; (u) engaging the sealing rams on the second subassembly; and (v) detaching the portion of the perforating gun string from the coiled tubing.
 18. The method of claim 17, wherein the conveyance extends through at least a portion of the lubricator, and wherein steps (a) and (b) comprise: (w) repeating steps of (i)-(v) as desired until a final perforating gun assembly is attached to a penultimate perforating gun assembly, and thereby forming the perforating gun string, wherein at least one of the first and final perforating gun assemblies comprise a firing head, and wherein the final perforating gun assembly optionally comprises a corresponding subassembly; (x) disengaging the sealing rams from a subassembly of the penultimate perforating gun assembly; (y) conveying the perforating gun string with the coiled tubing to a desired location within the wellbore; and (z) actuating the firing head.
 19. The method of claim 17, wherein the conveyance extends through at least a portion of the lubricator, and wherein steps (a) and (b) comprise: (1) attaching a first portion of the first perforating gun assembly to the conveyance; (2) conveying the first portion of the first perforating gun assembly through a portion of the lubricator; (3) attaching a second portion of the first perforating gun assembly to the first portion of the first perforating gun assembly; and repeating steps (2) and (3) for additional portions of the first perforating gun assembly until the first perforating gun assembly is assembled and contained within the lubricator.
 20. The method of claim 17, wherein the subassemblies are at least one of an isolation subassembly and a detonation transfer subassembly.
 21. The method of claim 17, wherein at least a portion of the wellbore is a deviated wellbore.
 22. The method of claim 17, wherein the first perforating gun assembly is the penultimate perforating gun assembly and the second perforating gun assembly is the final perforating gun assembly. 